From the earliest days of Islam, Muslim scholars made use of the Quran and prophetic hadiths to bolster their theological discussions of religious topics. None the less, the core of their theories derived from their own views and ideas. These were influenced by their perception of the Quran as well as by their intellectual and religious orientations, which were, in turn, determined by their personalities and the intellectual circles within which they moved, as well as by the background of the culture or intellectual heritage from which they hailed. As regards the degree of openness in embracing the teachings of other religions during the early days of Islam, it is safe to say that the Companions and Successors were quite receptive to wisdom literature and the stories of prophets which contributed to the Muslims’ knowledge of the religious cultures of Jews, Christians and Iranians; a knowledge that was later used in the elaboration of ethical ideas and exegetical investigations of the Quran. However, the same openness was not displayed when it came to the creedal teachings of these religions. This much may be said that the prophetic hadith, “wisdom is the lost object of the faithful, which he embraces wherever he finds it,” was heeded more in connection to matters of ethics and exegesis than to religious beliefs; at least in the first century after hijrah. The surviving accounts from the days of the Successors create the impression that the broad theological discussions about divine unity and justice were the results of disputations between Muslim scholars and those from among the ahl al-kitab (the People of the Book, i.e. Jews, Christians and Zoroastrians). For instance, discussions relating to the negation of a material body for God and about predestination were prompted by questions posed by the Jews of Yemen and the Christians of Syria. In particular, the latter discussion is a clear indication of the influence received by Muslim theologians from certain teachings of the People of the Book in the 1st century AH. Muslim b. Yasar (d. 100 AH) is of the opinion that Ma`bad Juhani’s views on predestination is in concord with the Christian position (Muslim b. Yasar p. 109). Painting a clear picture of the theological atmosphere of the 1st century AH is a well nigh impossible task owing to the paucity of the surviving material. Undoubtedly, the oldest evidence of the religious beliefs of the period, apart from what is in the Quran and sunnah, must be sought in the hadiths reported by the Companions of the Holy Prophet (PBUH). However, except scattered references in some of their remarks, the most extensive accounts of the prevalent theological issues of the time are contained in the sermons attributed to Imam `Ali (PBUH). Needless to say, only those hadiths are to be relied upon which are backed by authentic isnad (sing. sanad: chain of transmission). The predominant theological themes in hadiths reported from the Imam are those relating to the divine unity and negation of material attributes to God, all of which are underscored by Quranic allusions. The notion of predestination (qadar) appears to have been paramount on the minds of the scholars of the Companions’ era. An investigation of traditional sources points to the fact that these works, in addition to containing the remarks of the Holy Prophet (PBUH) on the subject of predestination reported by his Companions, include the latter’s views on the subject as well. For example, hadiths reported by such prominent Companions as Ibn Abi Ka`b, Ibn Mas`ud and `Ibadah b. Samit present a straightforward picture, free from abstruse theological intricacies, in which divine providence is affirmed as a reality. Complex discussions of the topic can only be found in a handful of hadiths. For instance, in a hadith of Imam `Ali (PBUH) the inevitability of qada (destiny) is asserted as opposed to the certainty of qadar (determination) and the argument is advanced that otherwise the reward and punishment in afterlife, and the notion of w`ad and wa`id (promise (of paradise) and threat (of hell)), would become untenable. Apart from a number of purely theological discussions, such as the negation of material attributes to God which were hardly touched upon especially in the period of the Companions, political topics like imamate and ethico-theological subjects such as the status of sinners occupied center stage in the Muslim scholarly circles of the 1st century AH. While the discussions of the first category were the result of theorization of religious ideas and beliefs, examples of which existed in the theological schools of previous religions, the discussions of the second group were the direct outcome of the events taking place in the 1st century of the Islamic era, especially those of the first fifty years. Though the scope of discussion of purely theological issues came to assume much greater proportions in the coming centuries the single most prominent theological dispute in the 1,500 years of Islamic history remains the division between the Shi`ites, the Muhakkimah, and the remaining majority of the Muslim community who later came be known as ahl al-sunnah wa ’l-jama`ah (the partisans of sunnah and consensus, i.e. the Sunnis). Many of the sources of divergence between these groups hark back to the politico- and ethico-theological issues of the 1st century AH.